Separating-prism telemeter.



A. KO'NIG.

SEPARATING PRISM TELEMETER.

APPLICATION FILED APR.28, 1908.

940, 166. Patented Nov. 16,1909.

2 SHEETS-SHEET 1.

A. KUNIG. SEPARATING PRISM TELEMETER. APPLICATION FILED APR.28, 1908.

940,166. Patented Nov. 16, 1909.

2 SHEETS-SHEET 2.

UNITED srnrns PATENT OFFICE. I

ALBERT KGNIG, OF J ENA, GERMANY, ASSIGNOR TO THE FIRM 0F CARL ZEISS, OFJENA,

' GERMANY.

SEPARATING-PRISM TELEMETER.

Specification of Letters Patent. Patentd Nov. 16, 1909.

Application filed April 28, 1908. Serial No. 429,613.

To all whom it may concern:

Be it known that I, ALBERT KoNIG, a citizen of the German Empire, andresiding at (larl-Zeiss strasse, Jena, in the Grand Duchy ofSaxe-Weime'r, Germany, have invented a new and useful Separating-PrismTelemeter, of which the following is a specification.

The invention relates to telemeters having two objectives, a commonocular and a separating prism system. Two such kinds of separating prismtelemeters are known: the coincidence telemeter in the narrower sense ofthe word and the symmetry telemeter according to our application forpatent, filed June 23, 1906, Serial No. 323,164. The invention extendsto both the said kinds, but only where the instrument has a horizontalbase line and the entrance pupils elevated so as to enable observationsbeing made and measurements taken over some obstacle sheltering theobserver.

The invention consists in a general arrangement for such telemeters,which is very simple and retains the approved arrangement of theordinary instrument, having non-elevated entrance pupils, for thoseparts, upon the position of which the accuracy of the measurementdepends.

A coincidtence telemeter with separating prism system and elevatedentrance prisms has been already touched upon in the patentspecification 661968 (page 2, column 1, lines 50 to 54) in connectionwith the detailed explanation of a telemeter, whose base line is alsohorizontal and whose single objective has a vertical direction 'of axisand lies be: low the level of the entrance prisms. With reference to thearrangement of the coin- 1 cidence telemeter with elevated entranceprisms incidentally mentioned, there is nothing set forth except thatthe separating prismsystem serves at the same time for reerecting theimage s (page 2, column 1,

lines 37 to 89). The simple solution of the same problem is according tothe present invention. based upon a lens inverting system erecting theimages projected'by the objectives. 'By such a system an astronomicaltelescope is in general elongated by a length equal to four times thefocal length of the system. If in the present instrument this length,which extends from the image plane of the objectives to that of theocular, be.'given a downward direction for the whole or a greater partof the way, it supplies in itselfin suitably choosing the focal lengthof the inverting lens systemthe required difference in level between theexit pupil and the entrance pupils. From that it follows, however, thatall those optical parts, which have influence upon the relative positionof the images produced by the objectives, that is to say, in all casesthe objective prisms and theseparating prism system as well as theobjectives, preserve the same identical level and can be assembled in arigid tube system as in the ordinary instrument with non-elevatedentrance pupils. But the position of the separating prism system candeviate so far from the ordinary one as to permit'uniting of the opticalaxes by this system also in a vertical plane. The united axis need thenonly be deflected once again by reflection, to make it horizontal andavailable as the ocular axis.

In the annexed drawing: Figure 1 is a perspective diagram of acoincidence telem eter constructed according to the invention. Fig. 2is. a similar diagramof another coincidence telemeter. Fig. 3 is adiagram of a symmetry telemeter. Fig. 4 is a diagram of anothersymmetrytelemeter. Fig. 5 is a longitudinal vertical section through acoincidence telemeter, in which the optical arrangement shown in Fig! 2is made use of.

In the example Fig. 1 two optical square prisms a are arranged in frontof the objectives b. The separating prism composed of two prisms c and dcemented together defleets the two optical axes in their horizontalplane and combines them in the common focus of the objectives which liesin the upper margin of the silver film (indicated by cross-hatching)serving as the separating surface. In this arrangement of the separatingsurface the under half of the inverted image projected from the rightobjective is combined, in the plane through the focal point at rightangles to the combined axis, with the upper half of the inverted imageprojected by the left objective into an inverted total image. Inmeasuring, the under partial image is moved in a horizontal direction,for which purpose a refractin' prism e movable along the axis isprovidecI. The combined axis emerging from the separating prism isdeflected downward by a reflecting prism f and passes then through theinverting lens g. The reflecting prism it provided with a ridge gives itfinally the horizontal emerging direction, in which a Ramsden ocularconsisting of the field lens 2' and the eye lens is is arranged. The sumtotal of all reflections through the prisms of hinder image field, whichmay coincide with the hinder surface of the prism h, the movable partialimage originating from the right objective lies above.

The separating prism system Z m of the second coincidence telemeter,Fig. 2, consummates the combination of the optical axes in a verticalplane. The common focal point, being also the combination point of theaxes, lies in the lower edge of the separating surface, and' this edgelies in the exit surface of the separating prism. The prism m isprovided with a rid e, so that the two partial images correspond to oneanother in respect of right and left. The prism n in front of the oculardiffers from the prism h in Fig. 1 not only by lacking a ridge, but

also by its position, by virtue of which the emerging section of theoptical axis remains in the vertical plane of the former sections. Theobserver sees in the upper half of the field of. view the movablepartial image coming from the right objectlve.

The symmetry telemeter Fig. 3 is provided with a separating prism 0 p,whioh combines the axes in the horizontal plane, the combined axis,however, being immediately de flected downward by a reflecting surfaceon the prism p, which-corresponds to the reflecting surface of the prismf in Fig. l. A simple reflecting prism 9 gives the axis then thehorizontal direction of emergence. In thev field of view of the observerthe two partial images abut on one another in a Witnesses:

movable image .is affected with the horizontal inversion. J

As in the construction Fig. 5 the optical parts according to Fig. 2 areemployed, this figure needs nofurther explanation.

. The separating prisms shown and described belong to the same class.Separating prisms of any class may besubstituted for them. Also insteadof the inverting lens consisting of three-parts cemented together a morecomposite inverting lens system may be employed.

I claim:

1. A horizontal separating prism telemeter with elevated entrancepupils, comprisin two objectives reflecting p'risms .for suitablydeflecting the optical axes individually, a separating prism system, anocular, an inverting lens system arranged with vertical axis between theseparating prism system and the occular, and means for moving one of theimage's projected by the objectives.

1 2. A horizontal separating prism telemeter with elevated entrancepupils, comprisring two objectives, two optical square prisms, aseparating prlsm system adapted to combine, in a vertical plane, the twooptical axes vproceeding from the objectives and the optical squareprisms, an inverting lens system placed on the combined optical axis, a.reflecting prism adapted to deflect the combined axis intoa directionparallel to the base line, an ocular and means for moving one of theimages projected by the obj ectives. u

ALBERT KONIG.

. PAUL KRr'ioER, Farrz SANDER.

